During seismic exploration of marshy terrains, geophone cases are implanted in the mud for detecting reflected seismic waves. The case is typically cylindrical and is provided with a conical nose, and a reduced-diameter, cylindrical section which is received by a tool that implants the case in the mud. An electric cable passes in a water-tight fashion through a bore in the cylindrical section. The wires of the cable are connected electrically to the terminals of a geophone housed by the case. It is common practice to provide suitable anchoring means in the internal chamber of the case to prevent the cable from being pulled out from the case.
After the seismic shooting is over, the geophone cases are retrieved from the mud by pulling on their cables. Each cable is adapted to withstand a very hard pull. Strong cables are rated to withstand a pull on the order of 400 pounds. It is therefore essential to properly anchor the cable to the case to prevent a hard pull from breaking the electric connections between the cable and the encased geophone. Various anchors have been proposed and used from simple knots to complicated devices. The known anchors are characterized by certain drawbacks chief among which are; they are difficult to fit inside the case, they are not sufficiently strong, they require special tools for guiding them into the interior chamber of the case, they damage the cable in response to a hard pull, and they are difficult to remove from the chamber of the case for repairs.